A method for regulating a light source of a microscope that illuminates an object, said method including specifying an intended value of an energy parameter of illumination radiation on the object; producing illumination radiation; providing an objective for focusing illumination radiation onto the object; ascertaining a transmission property of the objective for the illumination radiation; output coupling a component of the illumination radiation upstream of the objective as measurement radiation and measuring an actual value of the energy parameter of the measurement radiation; providing a relationship between energy parameters of the measurement radiation and energy parameters of the illumination radiation on the object, and setting the light source in such a way that the actual value of the energy parameter measured for the measurement radiation corresponds to the intended value of the energy parameter according to the relationship.